Annotation of freem/src/shmmgr.c, revision 1.11
1.1 snw 1: /*
1.11 ! snw 2: * $Id: shmmgr.c,v 1.10 2025/04/15 19:26:13 snw Exp $
1.1 snw 3: * shared memory manager
4: *
5: *
1.3 snw 6: * Author: Serena Willis <snw@coherent-logic.com>
1.1 snw 7: * Copyright (C) 1998 MUG Deutschland
1.4 snw 8: * Copyright (C) 2020, 2025 Coherent Logic Development LLC
1.1 snw 9: *
10: *
11: * This file is part of FreeM.
12: *
13: * FreeM is free software: you can redistribute it and/or modify
14: * it under the terms of the GNU Affero Public License as published by
15: * the Free Software Foundation, either version 3 of the License, or
16: * (at your option) any later version.
17: *
18: * FreeM is distributed in the hope that it will be useful,
19: * but WITHOUT ANY WARRANTY; without even the implied warranty of
20: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21: * GNU Affero Public License for more details.
22: *
23: * You should have received a copy of the GNU Affero Public License
24: * along with FreeM. If not, see <https://www.gnu.org/licenses/>.
25: *
1.5 snw 26: * $Log: shmmgr.c,v $
1.11 ! snw 27: * Revision 1.10 2025/04/15 19:26:13 snw
! 28: * Remove extra whitespace
! 29: *
1.10 snw 30: * Revision 1.9 2025/04/15 16:49:36 snw
31: * Make use of logprintf throughout codebase
32: *
1.9 snw 33: * Revision 1.8 2025/04/14 19:46:18 snw
34: * Add SHM_REMAP flag to shmat on FreeBSD
35: *
1.8 snw 36: * Revision 1.7 2025/04/09 19:52:02 snw
37: * Eliminate as many warnings as possible while building with -Wall
38: *
1.7 snw 39: * Revision 1.6 2025/04/04 19:43:18 snw
40: * Switch to using environment catalog to determine user and group for environment, and remove -u and -g flags from freem
41: *
1.6 snw 42: * Revision 1.5 2025/03/24 02:56:50 snw
43: * Shared memory compatibility fixes for OS/2
44: *
1.5 snw 45: * Revision 1.4 2025/03/09 19:50:47 snw
46: * Second phase of REUSE compliance and header reformat
47: *
1.4 snw 48: *
49: * SPDX-FileCopyrightText: (C) 2025 Coherent Logic Development LLC
50: * SPDX-License-Identifier: AGPL-3.0-or-later
1.1 snw 51: **/
52:
53: #include <stdlib.h>
54: #include <stdio.h>
55: #include <assert.h>
56: #include <string.h>
57: #include <unistd.h>
58: #include <errno.h>
59: #include <signal.h>
60:
61: #include "shmmgr.h"
62: #include "mpsdef.h"
63: #include "locktab.h"
1.9 snw 64: #include "log.h"
1.1 snw 65:
66: #include <sys/types.h>
67: #include <sys/ipc.h>
68: #include <sys/sem.h>
69:
1.5 snw 70: #if !defined(__OpenBSD__) && !defined(__APPLE__) && !defined(__OS2__)
1.1 snw 71: union semun {
72: int val; /* Value for SETVAL */
73: struct semid_ds *buf; /* Buffer for IPC_STAT, IPC_SET */
74: unsigned short *array; /* Array for GETALL, SETALL */
75: struct seminfo *__buf; /* Buffer for IPC_INFO
76: (Linux-specific) */
77: };
78: #endif
79:
80: int semid_shm;
81: extern int semid_locktab;
82: extern int semid_jobtab;
83: extern int semid_tp;
84: extern int semid_symtab;
85:
86: void shm_daemon_init(void);
87:
88: shm_config_t *shm_config = (shm_config_t *) NULL;
89:
90: short shm_init(const size_t seg_size)
91: {
92: size_t alloc_map_size;
93: long pg_size;
94: key_t shm_sk;
95:
96: shm_sk = ftok (config_file, 5);
97: pg_size = sysconf (_SC_PAGESIZE);
98:
99: shm_config = (shm_config_t *) malloc (sizeof (shm_config_t));
100: NULLPTRCHK(shm_config,"shm_init");
101:
102: /* figure out how many pages we can fit in the segment, accounting for header size */
103: shm_config->pgct = (seg_size / pg_size) - sizeof (shm_hdr_t);
104:
105: /* how big will the alloc map be? */
106: alloc_map_size = shm_config->pgct * sizeof (shm_page_t);
107:
108: shm_config->segsiz = seg_size + alloc_map_size + pg_size;
109: shm_config->key = ftok (config_file, 1);
110: shm_config->pgsiz = pg_size;
111:
1.6 snw 112: shm_config->seg_id = shmget (shm_config->key, shm_config->segsiz, 0770 | IPC_CREAT);
1.1 snw 113: if (shm_config->seg_id == -1) {
114: if (errno == 22) {
1.9 snw 115: logprintf (FM_LOG_ERROR, "shm_init: cannot get shared memory segment of %ld bytes", (unsigned long) shm_config->segsiz);
116: fprintf (stderr, "\r\nYou may need to tune your kernel parameters, or manually set a smaller shared memory segment size in both the FreeM daemon and each interpreter process by using the `-S` command-line flag.\r\n\r\nPlease refer to the FreeM Platform Notes for your operating system for details.\r\n");
1.1 snw 117: }
118: return SHMS_GET_ERR;
119: }
120:
121: #if !defined(__arm__)
122: shm_config->dta = shmat (shm_config->seg_id, NULL, 0);
123: #else
124: shm_config->dta = shmat (shm_config->seg_id, (void *) 0x1000000, 0);
125: #endif
126:
127: if (shm_config->dta == (void *) -1) {
128: return SHMS_ATTACH_ERR;
129: }
130: /* view the first sizeof (shm_hdr_t) bytes of the data area as an shm_hdr_t */
131: shm_config->hdr = (shm_hdr_t *) shm_config->dta;
132:
133: if (shm_config->hdr->magic != shm_config->key) {
134:
135: /* the shm segment is brand new */
136: first_process = TRUE;
137:
138: shm_daemon_init ();
139:
140: }
141: else {
142:
143: /* this shared mem segment was initialized before */
144: int daemon_chk;
145:
146: /* check if the daemon recorded in the header is actually running */
147: daemon_chk = kill (shm_config->hdr->first_process, 0);
148:
149: if (daemon_chk == -1 && errno == ESRCH) {
150:
1.9 snw 151: logprintf (FM_LOG_WARNING, "shm_init: recovering from crashed daemon pid %ld", shm_config->hdr->first_process);
1.1 snw 152:
153: first_process = TRUE;
154:
155: shm_daemon_init ();
156:
157: }
158: else {
159:
160:
161: first_process = FALSE;
162:
163: semid_shm = semget (shm_sk, 1, 0);
164: if (semid_shm == -1) {
1.9 snw 165: logprintf (FM_LOG_FATAL, "shm_init: could not attach to shared memory semaphore [%s]", strerror (errno));
1.1 snw 166: }
167:
168: /* we are NOT the initial process. if addresses don't match, re-attach! */
169: /* (again, borrowed from RSM) */
170: if (shm_config->hdr->shmad != shm_config->dta) {
171:
172: /* grab the pointers we need */
173: void *old_addr = shm_config->dta;
174: void *new_addr = shm_config->hdr->shmad;
1.11 ! snw 175:
! 176: logprintf (FM_LOG_INFO, "shmmgr: moving shared memory from %p to %p", old_addr, new_addr);
1.1 snw 177:
178: /* detach and reattach */
179: if (shmdt (old_addr) == -1) {
1.9 snw 180: logprintf (FM_LOG_FATAL, "shm_init: detach failed during detach/reattach [shmdt error %s]", strerror (errno));
1.1 snw 181: }
1.8 snw 182:
183: #if defined(__FreeBSD__)
184: shm_config->dta = shmat (shm_config->seg_id, new_addr, SHM_REMAP);
185: #else
186: shm_config->dta = shmat (shm_config->seg_id, new_addr, 0);
187: #endif
1.1 snw 188:
189: if (shm_config->dta == (void *) -1) {
1.9 snw 190: logprintf (FM_LOG_FATAL, "shm_init: fatal error attaching shared memory segment [shmat error '%s']", strerror (errno));
1.1 snw 191: }
192:
193: shm_config->hdr = (shm_hdr_t *) shm_config->dta;
194:
195: /* allocator buffer at the next page-aligned address after the header and allocation map */
196: shm_config->buf = SHMALIGN(shm_config->dta + (sizeof (shm_hdr_t) * shm_config->pgct));
197: }
198: else {
199: shm_config->buf = SHMALIGN(shm_config->dta + (sizeof (shm_hdr_t) * shm_config->pgct));
200: }
201:
202: }
203:
204: }
205:
206: locktab_init ();
207:
208: assert(shm_address_to_page_num(shm_page_num_to_address(20)) == 20);
209:
210:
211: return TRUE;
212: }
213:
214: void shm_daemon_init(void)
215: {
216: union semun arg;
217: key_t shm_sk;
218: register int i;
219:
220: shm_sk = ftok (config_file, 5);
221:
222: semid_shm = semget (shm_sk, 1, 0660 | IPC_CREAT);
223: if (semid_shm == -1) {
1.9 snw 224: logprintf (FM_LOG_FATAL, "shm_init: failed to create shared memory semaphore [%s]", strerror (errno));
1.1 snw 225: }
226:
227: arg.val = 1;
228: if (semctl (semid_shm, 0, SETVAL, arg) == -1) {
1.9 snw 229: logprintf (FM_LOG_FATAL, "shm_init: failed to initialize shared memory semaphore [%s]", strerror (errno));
1.1 snw 230: }
231:
232: /* zero out the segment */
233: memset (shm_config->dta, 0, shm_config->segsiz);
234:
235: /* we are the process that created the segment: initialize everything */
236: shm_config->hdr->magic = shm_config->key;
237: shm_config->hdr->first_process = pid;
238:
239: /* store the address we got into the shm_hdr (borrowed from RSM) */
240: shm_config->hdr->shmad = shm_config->dta;
241: shm_config->hdr->maintenance_mode = 0;
242:
243: /* alloc_map comes after the header */
244: /*
245: shm_config->alloc_map = (shm_page_t *) (shm_config->dta + sizeof (shm_hdr_t));
246: */
247: shm_config->buf = SHMALIGN(shm_config->dta + (sizeof (shm_hdr_t) * shm_config->pgct));
1.9 snw 248: logprintf (FM_LOG_INFO, "shm_daemon_init: allocator buffer aligned at %p (system page size %ld)", shm_config->buf, sysconf (_SC_PAGESIZE));
1.1 snw 249:
250: for (i = 0; i < shm_config->pgct; i++) {
251: shm_config->hdr->alloc_map[i].is_first = FALSE;
252: shm_config->hdr->alloc_map[i].is_last = FALSE;
253: shm_config->hdr->alloc_map[i].pg_state = PG_FREE;
254: }
255:
256: }
257:
258: short shm_exit(void)
259: {
260: int res;
261: union semun arg;
262:
263: res = shmdt (shm_config->dta);
264:
265: if (res == -1) {
1.9 snw 266: logprintf (FM_LOG_ERROR, "shm_exit: failure in shmdt() [%s]", strerror (errno));
1.1 snw 267: return FALSE;
268: }
269:
270: if (first_process) {
271:
272: res = shmctl (shm_config->seg_id, IPC_RMID, 0);
273:
274: if (res == -1) {
1.9 snw 275: logprintf (FM_LOG_ERROR, "shm_exit: failure in shmctl() [%s]", strerror (errno));
1.1 snw 276: return FALSE;
277: }
278:
279: semctl (semid_shm, 0, IPC_RMID, arg);
280: semctl (semid_locktab, 0, IPC_RMID, arg);
281: semctl (semid_jobtab, 0, IPC_RMID, arg);
282: semctl (semid_tp, 0, IPC_RMID, arg);
283: semctl (semid_symtab, 0, IPC_RMID, arg);
284:
285: }
286:
287: return TRUE;
288:
289: }
290:
291: short shm_get_sem(void)
292: {
293:
294: int tries;
295: struct sembuf s = {0, -1, 0};
296:
297: for (tries = 0; tries < 3; tries++) {
298:
299: if (semop (semid_shm, &s, 1) != -1) {
300: return TRUE;
301: }
302:
303: sleep (1);
304:
305: }
306:
307: return FALSE;
308:
309: }
310:
311: short shm_release_sem(void)
312: {
313: struct sembuf s = {0, 1, 0};
314:
315: if (semop (semid_shm, &s, 1) != -1) {
316: return TRUE;
317: }
318:
319: return FALSE;
320: }
321:
322: void shm_set_maintenance_mode (const short maintenance_mode)
323: {
324: if (shm_get_sem () == TRUE) {
325: shm_config->hdr->maintenance_mode = maintenance_mode;
326:
327: shm_release_sem ();
328: }
329: }
330:
331: shm_page_t *shm_get_alloc_map_entry(const int page_number)
332: {
333: return &(shm_config->hdr->alloc_map[page_number]);
334: }
335:
336: void *shm_page_num_to_address(const int page_num)
337: {
338: return (void *) shm_config->buf + (shm_config->pgsiz * page_num);
339: }
340:
341: int shm_address_to_page_num(const void *address)
342: {
343: unsigned long val = (unsigned long) address - (unsigned long) shm_config->buf;
344: unsigned long new_val = val / shm_config->pgsiz;
345:
346: return (int) new_val;
347: }
348:
349: void *shm_alloc_pages(const int page_count)
350: {
351:
352: register int i;
353: register int j;
354:
355: int candidate_page = 0;
356: int free_pages_gotten = 0;
357:
358: shm_page_t *pg;
359:
360: if (shm_get_sem () == FALSE) {
1.9 snw 361: logprintf (FM_LOG_FATAL, "shm_alloc_pages: could not get exclusive access to shared memory");
1.1 snw 362: }
363:
364:
365: for (i = 0; i < shm_config->pgct; i++) {
366:
367: pg = shm_get_alloc_map_entry (i);
368: NULLPTRCHK(pg,"shm_alloc_pages");
369:
370: free_pages_gotten = 0;
371:
372: if (pg->pg_state == PG_FREE) {
373:
374: candidate_page = i;
375:
376: for (j = i; ((j < (i + page_count)) && (j < shm_config->pgct)); j++) {
377: pg = shm_get_alloc_map_entry (j);
378:
379: if (pg->pg_state == PG_FREE) free_pages_gotten++;
380:
381: }
382:
383: if (free_pages_gotten == page_count) {
384:
385: for (j = candidate_page; j < (candidate_page + page_count); j++) {
386: pg = shm_get_alloc_map_entry (j);
387:
388: pg->pg_state = PG_ALLOC;
389: pg->pid = pid;
390:
391: if (j == candidate_page) {
392: pg->is_first = TRUE;
393: }
394:
395: if (j == candidate_page + (page_count - 1)) {
396: pg->is_last = TRUE;
397: }
398:
399: }
400:
401: shm_release_sem ();
402:
403: return (void *) shm_config->buf + (shm_config->pgsiz * candidate_page);
404:
405: }
406:
407: }
408:
409: }
410:
411: shm_release_sem ();
412:
413: return (void *) NULL;
414:
415: }
416:
417:
418: void *shm_alloc(const size_t bytes)
419: {
420: int pages_needed = bytes / shm_config->pgsiz;
421: float extra = bytes % shm_config->pgsiz;
422:
423: if (extra > 0) {
424: pages_needed++;
425: }
426:
427: return shm_alloc_pages (pages_needed);
428: }
429:
430: void shm_free_page(const int page_number)
431: {
432: register int i;
433: shm_page_t *a = shm_get_alloc_map_entry (page_number);
434:
435: if (a->is_first == FALSE) {
1.9 snw 436: logprintf (FM_LOG_ERROR, "shm_free_page: attempt to free page in the middle of allocation chain");
1.1 snw 437: return;
438: }
439:
440: if (a->pg_state == PG_FREE) {
1.9 snw 441: logprintf (FM_LOG_FATAL, "shm_free_page: double free attempted in page %d", page_number);
1.1 snw 442: }
443:
444: if (shm_get_sem () == FALSE) {
1.9 snw 445: logprintf (FM_LOG_FATAL, "shm_free_page: could not get exclusive access to shared memory");
1.1 snw 446: }
447:
448:
449: for (i = page_number; i < shm_config->pgct; i++) {
450:
451: a = shm_get_alloc_map_entry (i);
452:
453: if (a->is_last) {
454: a->is_first = FALSE;
455: a->pg_state = PG_FREE;
456: a->pid = 0;
457: a->is_last = FALSE;
458:
459: shm_release_sem ();
460:
461: return;
462: }
463: else {
464: a->is_first = FALSE;
465: a->pg_state = PG_FREE;
466: a->pid = 0;
467: a->is_last = FALSE;
468: }
469:
470: }
471:
472: shm_release_sem ();
473:
474: }
475:
476: void shm_free(const void *addr)
477: {
478: shm_free_page (shm_address_to_page_num (addr));
479: }
480:
481: void shm_dump(void)
482: {
483:
484: printf ("SHARED MEMORY CONFIGURATION\r\n");
1.2 snw 485: printf (" pgsiz %ld\r\n", (unsigned long) shm_config->pgsiz);
1.1 snw 486: printf (" pgct %d\r\n", shm_config->pgct);
1.7 snw 487: printf (" key %d\r\n", shm_config->key);
1.1 snw 488: printf (" segid %d\r\n", shm_config->seg_id);
1.2 snw 489: printf (" sizeof shm_page_t %ld\r\n", (long) sizeof (shm_page_t));
490: printf (" segsiz %ld\r\n", (long) shm_config->segsiz);
1.1 snw 491: printf (" shm address %p\r\n", shm_config->dta);
1.2 snw 492: printf (" alloc_map size %ld\r\n", (unsigned long) sizeof (shm_page_t) * shm_config->pgct);
1.1 snw 493: printf (" buf address %p\r\n", shm_config->buf);
494: }
495:
496: void shm_dump_pages(void)
497: {
498:
499: register int i;
500: shm_page_t *p;
501:
502: printf ("%-10s%-10s%-10s%-10s%-10s\r\n", "PAGE", "PID", "BMHEAD", "BMTAIL", "STATE");
503:
504: for (i = 0; i < shm_config->pgct; i++) {
505:
506: p = shm_get_alloc_map_entry (i);
507:
508: printf ("%-10d%-10d%-10s%-10s%-10s\r\n",
509: i,
510: p->pid,
511: (p->is_first == TRUE) ? "Y" : "N",
512: (p->is_last == TRUE) ? "Y" : "N",
513: (p->pg_state == PG_FREE) ? "PG_FREE" : "PG_ALLOC");
514:
515: }
516:
517: }
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